An internal combustion engine is provided with a fuel injection valve injecting fuel in each cylinder. A general fuel injection valve has a solenoid and a movable core. The fuel injection valve is opened or closed as a valve body inside the fuel injection valve moves integrally with the movable core.
The injection control device controls the fuel injection valve such that the amount of fuel injected from the fuel injection valve (that is, the amount of fuel injected during a period from opening of the fuel injection valve to closing thereof) matches a target value. Specifically, the injection control device adjusts the duration, magnitude, and the like of a driving current supplied to the fuel injection valve to adjust the valve opening time of the fuel injection valve and match the amount of fuel injected with the target value.
When a plurality of fuel injection valves is provided in the internal combustion engine, the amount of fuel injected from each fuel injection valve may vary due to individual differences and deterioration of the fuel injection valves, the ambient temperature, and the like. It is thus necessary to adjust the duration and the like for supplying the driving current and reduce the variations in the amount of fuel injected from the fuel injection valves. In order to control the actual amount of fuel injected, the start and end of the movement of the valve body need to be detected in a valve opening operation of the fuel injection valve.
A control device described in Patent Literature 1 detects the start of the movement of a valve body on the basis of a change in a driving current supplied to a fuel injection valve. Specifically, a movement of a movable core together with the valve body causes a change in inductance and thus a change in the driving current. The control device described in Patent Literature 1 differentiates the driving current with respect to time and detects the start of the movement of the movable core on the basis of the differential value.